High incidence and prevalence of MS in Møre and Romsdal County, Norway, 1950-2018.

ObjectiveTo determine prevalence and longitudinal trends in incidence of MS in Møre and Romsdal County, Western Norway, from 1950 to 2018.MethodsRetrospective longitudinal population-based observational study. All patients diagnosed, or living, with MS in Møre and Romsdal were identified as incident or prevalent cases from local, regional, and national sources. We compiled the data in the Norwegian Multiple Sclerosis Registry and Biobank and used the aggregated data set to calculate incidence and prevalence rates using population measures obtained from Statistics Norway.ResultsOn January 1, 2018, the estimated prevalence was 335.8 (95% CI, 314.1-358.5) per 100,000 inhabitants, with a female:male ratio of 2.3. From 1950 through 2017, we observed a considerable (p ConclusionMøre and Romsdal County in Western Norway has the highest prevalence of MS reported in Norway. The incidence has steadily increased since 1950, and during the latest 15 years, we observed opposing trends in sex-specific incidence rates.